The present invention relates generally to wireless telecommunications and more particularly to a system and method for implementing hard handover in a wireless telecommunications system such as a Universal Mobile Telecommunications System.
A major effort has been made in the last decade to integrate multimedia capabilities and wireless (or mobile) communications. For example, the International Telecommunications Union and other organizations have been developing standards and recommendations to insure that mobile communications in the future will be able to support multi-media applications of at least the same quality as existing fixed networks. More specifically, many global research projects have been sponsored in order to develop such third generation (3G) mobile systems. 3G systems are intended to provide a global mobility with wide range of services including telephony, paging, messaging, Internet and broadband data. In particular, the 3rd Generation Partnership Project (3GPP) was formed for technical development relating to this new mobile communications technology. The Universal Mobile Telecommunications System (UMTS) is a new radio access network, which is optimized for support of 3G services, including multi media-capable mobile communications.
A UMTS network generally includes a number of base stations, with the base stations being linked (by radio) to user equipment, whose location may change within a given geographical area. However, once the user equipment moves away from the radio coverage area of a particular base station, the call to the user equipment is taken over by another base station. The occurrence of a change of base stations may be detected by any of known means in the art, such as measuring call traffic volume, user equipment transmission power and signal levels, call signal quality, or the position of the user equipment. If such an occurrence is detected, a call “handover” may be necessary.
Under the UMTS standards, which are described in detail in a number of technical specifications put out by 3GPP, under certain conditions the UMTS network must ensure that a hard handover is achieved. Hard handover is generally defined as a category of handover procedures whereby all of the old radio links in the user equipment are abandoned after new radio links are successfully put into service. In other words, mobile connections are to be maintained while the subscriber is moving. However, the UMTS standards do not specify how to implement these important concepts. Thus, there is a need in the art to provide an implementation of the UMTS standards for providing hard handover in a UMTS network. Further, there is a need for a system and method whereby the manipulation of the bearer path during hard handover occurs without impacting the far party endpoint and without concern for any actions transpiring at that other endpoint. The other endpoint could be another wireless subscriber or a public switched customer.